This invention relates generally to a double-hung window assembly having pivotal sashes and more particularly, to an improved sash constructed from extruded plastic framing members having novel latching and pivotal means associated therewith at the miter joints of the sash.
Known double-hung window assemblies provide for inward tilting or pivoting of the two sashes by means of rotating members at the bottom ends of the sash balance mechanisms located in the jambs of the master window frame. Each sash has a pair of pivot pins or the like connected to the rotating member for rotation of the sash around a lower pivotal axis. Alternatively, the sash balance mechanisms provide pins received at the lower margin of the sashes. Normal vertical reciprocal movement of the sashes is maintained by latch mechanisms disposed at the top margins of the sashes. The latch mechanisms usually include some manner of latch bolts that can slide along guide rails extending vertically of the master frame jambs. Releasing the latch mechanisms permits the sash to be pivoted inwardly for cleaning and/or servicing of the window glass pane.
Recently, such window assemblies and sashes have been formed of extruded synthetic plastic in order to reduce manufacturing and maintenance costs. In U.S. Pat. No. 4,144,674, extruded plastic members of one, uniform, cross-sectional configuration are fabricated to form the master frame while extruded plastic members of another, uniform cross-sectional configuration are fabricated to form the frame of each sash. Each sash has two latching mechanisms fastened onto the top surface of the header and two pivot pins fastened onto the bottom surface of the base,. The sash frames have miter-jointed corners. Hollow configurations of the sash framing members function to provide insulation against heat loss through the sash frame.
Fabrication of such a frame occurs by inserting the four frame members in a jig and clamping them together until the adhesive at the miter-joints sets. This requires waiting time for setting of the adhesive; and further perfectly joined corners are a very difficult and often inconsisent achievement. As often ocurs, the extruded members are slightly warped or mitered imperfectly so that mating end edges that are intended to abut fail to do so. The result is non-mating miter joint end edges that are readily discernable because of the slivers of light that can pass through the joint in a direction normal to the plane of the sash. Such slivers of light leakage signal air and heat leakage rendering the particular sash undesirable for use in a home or office where heating costs are important.
Further, the completion of such a sash requires the addition of the latch mechanisms and pivot pins, including the proper location of the pivot pins for proper insertion in the sash balance mechanisms, but non-interference with the master frame jambs.
Heretofore, the latch mechanisms have been applied external of the sash header with a suitable covering or guiding plate, or if internal, in a groove of the header, with a similar covering or guiding plate to close the groove. These covers and/or grooves add to the cost of the sash.
It is thus desirable to reduce the cost of utilizing such latch mechanisms while eliminating the light leakage at miter joints and positively locating the pivot pins. It will be appreciated that manufacture and assembly of such sashes and window assemblies must be economical and of good consistent quality in order to be competitive. The large number of such window and sash structures used in the building industry requires such economical considerations.